Flammability and thermal degradation of epoxy acrylate modified with phosphorus‐containing compounds

A series of UV‐curable flame‐retardant resins was obtained by blending phosphate acrylate (BTP) in different ratios with epoxy acrylate resin (EA). The flammability was characterized by limiting oxygen index (LOI), UL 94 flammability rating and cone calorimeter, and the thermal degradation of the flame‐retardant resins was studied using thermo gravimetric analysis (TGA), and real‐time Fourier transform infrared (RTFTIR). The results indicated that the flame‐retardant efficiency increases with the addition of BTP. The heat release rate with the addition of BTP decreases greatly. The TGA data showed that EA/BTP blends have lower initial decomposition temperatures and higher char residues than pure EA, whereas BTP has the lowest initial decomposition temperature and the highest char residue. The RTFTIR study indicates that the EA/BTP blends have lower thermal oxidative stability than the pure EA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Different effects of tri(acryloyloxyethyl) phosphate on the thermal degradation of photopolymerized epoxy acrylate and polyurethane acrylate films

Tri(acryloyloxyethyl) phosphate (TAEP) was blended in different ratios with epoxy acrylate EB600 and polyurethane acrylate EB270 to obtain a series of UV curable flame retardant resins. The thermal degradation mechanisms of their cured films in air were studied by thermogravimetric analysis, in situ Fourier‐transform infrared spectroscopy, and direct pyrolysis/mass spectrometry measurements. The results showed that the phosphate group in TAEP first degraded to form poly(phosphoric acid) before the degradation of EB600. Then, the formed poly(phosphoric acid) effectively promoted the conversion of EB600 to form char, which prevented the sample from further burning. However, urethane group in EB270 degraded simultaneously with phosphate group in TAEP, leading to not effectively increase the conversion of EB270 to char during the thermal degradation. It was thus found that the addition of TAEP more effectively improved the thermal stability, flame retardance, and the char yield during combustion of EB600 than those of EB270. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3130–3137, 2006     

Synergistic effect of a novel charring agent with ammonium polyphosphate on flame retardancy and thermal degradation of acrylonitrile‐butadiene‐styrene copolymer

A novel charring agent poly(1,3‐propylene terephthalamide) (PPTA) was synthesized and characterized by Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance. This novel charring agent combined with ammonium polyphosphate (APP) was adopted as an intumescent flame retardant (IFR) to impart flame retardance and dripping resistance to acrylonitrile‐butadiene‐styrene copolymer (ABS). Flammability and thermal behaviors of the treated ABS were investigated by limiting oxygen index, vertical burning test and thermogravimetric analysis. The results showed that the IFR with the novel charring agent had both excellent flame retardant and anti‐dripping abilities for ABS. The thermogravimetric analysis curves indicated that there was a synergistic effect between PPTA and APP, which greatly promoted the char formation of IFR‐ABS composites. Meanwhile, the thermal degradation mechanism of PPTA and APP/PPTA was characterized using thermogravimetric analysis/infrared spectrometry. The results demonstrated that APP changed the thermal degradation behavior of PPTA and reacted with PPTA to form a crosslinked structure. Additionally, the structure and morphology of char residues were studied by Fourier transform infrared spectroscopy and scanning electron microscopy. Copyright © 2011 Society of Chemical Industry     

Flame retardancy,mechanical, and thermal properties of waterborne polyurethane conjugated with a novel phosphorous‐nitrogen intumescent flame retardant

A novel phosphorous‐nitrogen intumescent flame retardant with reactive diamino groups, benzoguanamine spirocyclic pentaerythritol bisphosphonate (BSPB), was synthesized and used as a chain extender, and then a series of flame retardant waterborne polyurethanes (FRWPU) were prepared by covalently conjugating the BSPB into waterborne polyurethane (WPU) backbone. Their structures were characterized by Fourier transformed infrared spectrometry (FTIR), ¹H and ³¹P nuclear magnetic resonances (NMR), respectively. Simultaneously, the flame retardancy and the thermal stability of FRWPU were systematically investigated by limiting oxygen index (LOI) test, UL‐94 vertical burning test and thermogravimetric analysis (TGA). The results indicated that with the increase of BSPB content from 0 to 8 wt%, the LOI value of FRWPU increased from 18.6 to 27.3%, showing significant improvement by 8.7%. Compared with WPU, FRWPU showed decreased thermal stability but promoted char residue ratio. Conjugation of BSPB could obviously enhance the mechanical properties of FRWPU, the Young's modulus and tensile strength dramatically increased with the increase of BSPB. Investigation of char forming mechanism of BSPB through real time Fourier transform infrared spectra (RTFTIR) and scanning electronic microscopy (SEM) revealed that the polyphosphoric acid and phosphorus oxynitrides rich outer intumescent char layer could form protective shields to inhibit effectively internal polyurethane to heat and flame diffusion during contacting fire. POLYM. COMPOS., 38:452–462, 2017. © 2015 Society of Plastics Engineers     

Component ratio effects of hyperbranched triazine compound and ammonium polyphosphate in flame‐retardant polypropylene composites

A hyperbranched derivative of triazine group (EA) was synthesized by elimination reaction between ethylenediamine and cyanuric chloride. The different‐mass‐ratio EA and ammonium polyphosphate (APP) were mixed and blended with polypropylene (PP) in a constant amount (25%) to prepare a series of EA/APP/PP composites. The component ratio effect of EA/APP on the flame‐retardant property of the EA/APP/PP composites was investigated using the limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimetry tests. Results indicated that the EA/APP/PP (7.50/17.50/75.00) composite with the appropriate EA/APP mass ratio had the highest LOI, UL94 V‐0 rating, lowest heat release rate, and highest residue yield. These results implied that the appropriate EA/APP mass ratio formed a better intumescent flame‐retardant system and adequately exerted their synergistic effects. Furthermore, average effective combustion heat values revealed that EA/APP flame retardant possessed the gaseous‐phase flame‐retardant effect on PP. Residues of the EA/APP/PP composites were also investigated by scanning electron microscopy, Fourier‐transform infrared, and X‐ray photoelectron spectroscopy. Results demonstrated that the appropriate EA/APP mass ratio can fully interact and lock more chemical constituents containing carbon and nitrogen in the residue, thereby resulting in the formation of a dense, compact, and intumescent char layer. This char layer exerted a condensed‐phase flame‐retardant effect on EA/APP/PP composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41006.     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Synthesis of a phosphorus‐ and nitrogen‐containing flame retardant and evaluation of its application in waterborne polyurethane

A phosphorus‐ and nitrogen‐containing intumescent flame retardant, pentaerythritol di‐N‐hydroxyethyl phosphamide (PDNP), was synthesized with phosphorus oxychloride, pentaerythritol, and ethanolamine as raw materials. Using the prepared PDNP as a chain extender, a series of flame‐retardant waterborne polyurethanes (WPU) were prepared, and their structures were characterized using NMR and Fourier transform infrared spectroscopy (FTIR). Additionally, the thermal properties and flame retardancy of WPU films were investigated by thermogravimetric analysis, limiting oxygen index (LOI) tests, cone calorimeter tests, and thermogravimetry‐FTIR. These results indicated that PDNP materials exhibit good char‐forming ability at high temperature and that PDNP‐modified waterborne polyurethane obtained an LOI value of 26.0% for a PDNP content of 9 wt %. Finally, the morphology and the element distributions of char residues of WPU were analyzed by scanning electron microscopy and energy dispersive spectrometry after combustion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46093.     

A commercial phosphorous–nitrogen containing intumescent flame retardant for thermoplastic polyurethane

The aim of this work is to develop a halogen‐free thermoplastic polyurethane (TPU) composite with significantly improved fire performance by using a highly commercial phosphorous–nitrogen containing intumescent flame retardant (P–N IFR). Based on the characterizations of thermogravimetric analysis and in situ Fourier transform infrared spectra, P–N IFR powder was proved a desired flame retardant for TPU in theory and the thermal degradation property of PU/PNIFR composites at elevated temperatures was investigated as well. Fire performance was evaluated by limiting oxygen index, underwriters laboratories 94 testing and char residue morphologies. Results showed that the addition of P–N IFR promotes the formation of char residues which were covered on the surface of polymer composites resulting in the improvement of thermal stability and flame retardancy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39772.     

Synthesis of a phosphorus and sulfur‐containing aromatic diamine curing agent and its application in flame retarded epoxy resins

A novel curing agent of epoxy resins (EPO), bis(3‐amino‐2‐thienyl) phenylphosphine oxide (ABTPPO), was synthesized and characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and ³¹P NMR. ABTPPO was used as a flame retardant curing agent, and a novel halogen‐free flame retardant EPO composite was prepared. The flame retardant properties of ABTPPO‐cured EPO were evaluated in terms of limiting oxygen index and vertical burning test (UL‐94), while the combustion and thermal degradation behaviors were investigated by cone calorimeter test (CONE) and thermogravimetric analysis, respectively. The cured EPO composite passed the UL‐94 V‐1 and V‐2 rating when the sample thickness is 3.0 and 1.6 mm, respectively, and the limiting oxygen index value reached 38.3%. The morphological structures of char residue tested by scanning electron microscopy demonstrated that ABTPPO benefited to the formation of a more compact and homogeneous char layer on the materials' surface during burning, which protected the underlying matrix from decomposition and enhanced the flame retardancy of materials. The cured EPO showed excellent fire performance after the water resistance test because of the low water uptake (0.6 wt%), which demonstrated that the flame retardant EPO composite possessed excellent water resistance property. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and film properties of tri(3,4-epoxycyclohexylmethyl) phosphate based cationically UV curing coatings

A facile synthesis of phosphorus-containing trifunctional cycloaliphatic epoxide resin, tri(3,4-epoxycyclohexylmethyl) phosphate (TECP), used for cationically UV curing coatings as a reactive-type flame retardant, was proposed. The molecular structure was confirmed by FTIR, ¹H NMR and ³¹P NMR spectroscopic analysis. A series of flame retardant formulations by incorporating into a commercial difunctional cycloaliphatic epoxide resin, CYRACURE™ UVR-6110, were prepared, and exposed to a medium pressure lamp to form the cured films under the presence of diaryliodonium hexafluorophosphate salt as a cationic photoinitiator. Their flame retardancy examined by the limiting oxygen index showed the improvement up to 27 for 50 wt% TECP addition compared with 21 for pure UVR-6110. The T_s and T_g decreased from 86 °C and 131 °C to 55 °C and 91 °C, respectively, by using dynamic mechanical thermal analysis, whereas the tensile strength showed a slight increase (11%) with 50 wt% TECP addition. The thermogravimetric analysis (TGA) and real-time Fourier transform infrared spectroscopy (RT-FTIR) measurement demonstrated the condensed-phase flame retardant mechanism.     

Synthesis of polysiloxane‐type multifunctional flame retardant and its application in epoxy systems

Polymethyl(3‐glycidyloxypropyl)siloxane (PMGS) was synthesized as a flame‐retardant additive, which were cocured with diglycidyl ether of bisphenol‐A (DGEBA) using 4,4′‐diaminodiphenylsulfone as a curing agent. The structure of PMGS was confirmed through Fourier transform infrared and ¹H‐NMR spectra. The cured products were characterized with dynamic mechanical thermal analysis, thermogravimetric analysis, and oxygen index analyzer. With PMGS incorporated, the cured epoxy resin showed better thermal stability, higher limited oxygen index, and higher char yield. At moderate loading of PMGS, the storage modulus and glass transition temperature of the cured epoxy resin based on neat DGEBA were obviously improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal behaviors of a novel UV cured flame retardant coatings containing phosphorus,nitrogen and silicon

Phosphorus‐containing trimethoxysilane (DGTH) was blended with Star polyurethane acrylate (SPUA) in different ratios to obtain a series of UV curable intumescent flame retardant resins. The fire properties were characterized by limiting oxygen index (LOI) and cone calorimetry. A distinct synergistic effect was found between SPUA and DGTH. The thermal degradation was characterized by thermogravimetric analysis and real time Fourier‐transform infrared spectroscopy. The TG results have been found to correlate well with the LOI results. A degradation mechanism has been suggested that the 9,10‐dihydro‐oxa‐10‐phosphaphenantrene‐10‐oxide (DOPO) group in DGTH first degraded to form poly(phosphoric acid)s, which further catalyzed the degradation of the material to form char with emission of nitrogen volatiles from SPUA, leading to the formation of expanding char. The morphologic structures of crusts of the formed chars were observed by scanning electron microscopy, confirming the synergistic effect between SPUA and DGTH. POLYM. ENG. SCI., 48:116–123, 2008. © 2007 Society of Plastics Engineers     

Preparation and characterization of surface‐modified ammonium polyphosphate and its effect on the flame retardancy of rigid polyurethane foam

A functional surface‐modification agent was synthesized via a reaction between hexachlorocyclotriphosphazene and γ‐aminopropyl triethoxysilane. Ammonium polyphosphate (APP) was modified with this agent and then incorporated into a rigid polyurethane foam (RPUF). Fourier transform infrared spectroscopy, ¹H‐NMR, and X‐ray photoelectron spectroscopy were used to characterize the modified ammonium polyphosphate (M‐APP). The results show that the dispersibility was improved and the particle size decreased after the modification. The limiting oxygen index and cone calorimetry test results show that M‐APP enhanced the flame‐retardant properties of RPUF. The peak heat‐release rate of polyurethane (PU)/20% M‐APP decreased by 51.18% compared with that of PU–APP. The scanning electron microscopy results illustrate that M‐APP facilitated the formation of intumescent and compact char. The excellent flame‐retardant performance of M‐APP resulted from the flame‐inhibition and barrier effects, which were attributed to the phosphazene group and the intumescent char, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45369.     

An effective intumescent flame retardancy of LDPE induced by the combination of APP and CNCO‐HA

A char‐forming agent poly(4,6‐dichloro‐N‐hydroxyethyl?1,3,5‐triazin‐2‐amine‐1,6‐diaminohexane) (CNCO‐HA) containing triazine rings was chosen for improving the flame retardant of low density polyethylene (LDPE). The synergistic effect of CNCO‐HA and Ammonium polyphosphate (APP) on the flame retardancy and char‐forming behavior of LDPE were investigated. The limited oxygen index (LOI) and vertical burning test (UL‐94) results indicated the optimal weight ratio of APP to CNCO‐HA was 3:1, and the LOI value of composite reached 31.0% with 30% intumescent flame retardant (IFR) loading. The cone calorimeter test analysis revealed that IFR presented excellent char forming and smoke suppression ability, and resulted in the efficient decrease of combustibility parameters. The thermogravimetric analysis results demonstrated that IFR reduced the thermal degradation rate at main stage of degradation. Scanning electron microscopy observed that IFR promoted to form a compact and continuous intumescent char layer. The Laser Raman spectroscopy spectra showed that larger graphitization degree was formed to enhance the strength of char, and Fourier transform infrared results presented that P‐O‐C and P‐O‐P structures in the residue char were formed to improve shield performance of the char layer to obtain better flame retardant properties of the composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43950.     

Synthesis,thermal degradation,and flame retardance of novel triazine ring‐containing macromolecules for intumescent flame retardant polypropylene

Two novel triazine ring‐containing macromolecules, designated as charring‐foaming agent 1 (CFA1) and charring‐foaming agent 2 (CFA2), were synthesized by a series of polycondensation reactions. Their chemical structures were analyzed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹³C solid‐state NMR), and elemental analysis, and their thermal degradation properties were assessed by thermogravimetric analysis (TGA). TGA data revealed that CFA1 and CFA2 show high thermal stability and have a high propensity for char formation, their initial decomposition temperatures being 300.2°C and 287.1°C, and their char residues at 800°C amounting to 32.2 wt % and 21.1 wt %, respectively. CFA1 presents higher thermal stability and more char residue than CFA2. Based on experimental results of the flame retardancy (limiting oxygen indices values and UL‐94 V‐0 rating) and the TG data of new intumescent flame retardant polypropylene (IFR‐PP) containing CFA1 and CFA2, CFA1 exhibits more outstanding intumescent flame retardance than CFA2. IFRs containing CFA1 and CFA2 enhanced Notched Izod Impact strength of IFR‐PP, and slightly lower tensile strength of IFR‐PP. IFR2 shows more advantageous effect on mechanical properties of IFR‐PP than IFR1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

新型环状含磷丙烯酸酯光固化单体的制备及性能研究

本文以新戊二醇、三氯氧磷、丙烯酸羟乙酯为原料,合成了新型环状含磷丙烯酸酯光固化树脂(ANP),红外光谱(FT-IR)和核磁共振氢谱(1H-NMR)结果证明成功合成了预期产物。将其与甲基丙烯酸化三聚氰胺(MAPM)、季戊四醇三丙烯酸酯(EM235)复配制得阻燃光固化涂料,对此涂料的阻燃性能、膨胀行为、热稳定性能进行研究,结果表明:随ANP添加量的增加光固化涂料的氧指数(LOI)值急剧升高,从23.5提高到29.5;当ANP、MAPM、EM235的质量比为35%∶25%∶40%时,极限氧指数LOI(29.5)值最高,阻燃性能最佳;加热过程中在不同质量比例下复配的涂料均有明显的膨胀行为。通过氧指数和加热过程中的膨胀效果发现三者之间存在协同效应;利用热失重分析研究其热稳定性,得出随着ANP含量的增加,涂料的初始分解温度降低,高温成炭量升高。     

Influence of ultrafine zinc borate on the thermal degradation behavior of a(low‐density polyethylene)/(intumescent flame retardant) system

The thermal degradation behavior of low‐density polyethylene (LDPE), LDPE treated with an intumescent flame retardant (LDPE/IFR), and LDPE treated with an intumescent flame retardant and ultrafine zinc borate (LDPE/IFR/UZB) was studied by (thermal gravimetric)‐(differential thermal) analysis (TG‐DTA) and cone calorimetry. The results of TG‐DTA showed that the initial degradation temperature increased, thermal degradation rate decreased, and the residual char amount increased substantially during the Pyrolysis process when ultrafine zinc borate was introduced into the LDPE/IFR system. The mass‐loss rate (MLR) curves and mass curves obtained by cone calorimetry showed that UZB could decrease the MLR and significantly enhance the residual char amount of LDPE/IFR during the combustion process. The results of Fourier transform infrared spectroscopy implied that a graphite‐like char and aromatic structures containing P‐O‐P, P‐O‐C, and B‐O‐B bonds were formed when LDPE/IFR/UZB was heated at high temperature. Scanning electronic micrographs of residual chars showed that ultrafine zinc borate improved char quality. X‐ray diffraction Studies implied that boron orthophosphate (BPO₄) formed in the residual char may play an important role in improving the structural properties of the char and is responsible for its good quality. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

A novel flame retardant UV‐curable vinyl ester resin monomer based on industrial dipentene: Preparation,characterization, and properties

A novel bio‐based and flame‐retardant UV‐curable vinyl ester resin (VER) monomer named Diglycidyl ester of maleinized dipentene modified with dibutyphosphate and methacrylic anhydride (MDDMD) was synthesized from industrial dipentene via Diels‐Alder reaction, glycidylation, epoxy ring‐opening reaction, and esterification. Its chemical structures were characterized by Fourier transform infrared (FTIR) analysis and proton nuclear magnetic resonance (¹H‐NMR). In order to improve its flexibility, we prepared a series of copolymers under UV light radiation by mixing it with certain proportions of poly(ethylene glycol) dimethacrylate‐200 (PEGDMA‐200) which contained flexible groups. Their tensile property, curing degrees (CD), hardness, limiting oxygen index (LOI), dynamic mechanical thermal properties, and thermostability were all investigated. The cured mixed resins have a relatively high tensile strength of 10.05 MPa and curing degrees up to 92.5%. Both hardness (range: 50 to 23 HD) and LOI (range: 22.8% to 24.4%) of cured resins are improved with the increase of MDDMD content. Dynamic mechanical analysis (DMA) shows that their glass transition temperatures rise with the increase of MDDMD content. Thermogravimetric analysis (TGA) shows that the thermal stability of cured resins is enhanced with the increase of PEGDMA‐200 content, as the main thermal initial decomposition temperatures are all above 260 °C and char yield at 800 °C are above 18.10%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44084.     

无卤膨胀阻燃剂在低密度聚乙烯中的应用研究

以干法合成的P-N无卤膨胀阻燃剂(IFR)为基础,配合聚磷酸胺(APP)并且将金属氧化物(ZnO)作为协效剂阻燃改性低密度聚乙烯(PE-LD)。采用扫描电子显微镜对该体系燃烧后的炭层结构进行了分析。通过红外光谱和X射线光电子能谱研究了该体系在不同温度热处理后的残炭组成,并分析了该膨胀型阻燃体系对PE-LD的阻燃机理。结果表明,PE-LD/IFR/APP/ZnO体系的极限氧指数可以达到27.9%,垂直燃烧性能达到UL 94V-0级。     

无卤阻燃聚乙烯醇缩甲醛纤维的制备与表征

以新戊二醇和三氯硫磷为原料,一步法合成了无卤膨胀型阻燃剂二硫代焦磷酸双新戊二醇酯(BGDTP);采用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(~1H-NMR)对BGDTP的结构进行了表征。将BGDTP添加到聚乙烯醇(PVA)中进行共混纺丝,制备了阻燃聚乙烯醇缩甲醛(PVFM)纤维,并对其力学性能、阻燃性能和热性能进行了表征。结果表明:一步法合成BGDTP的收率为82%;随着纤维中BGDTP添加量的增加,PVFM纤维的极限氧指数(LOI)、高温下的最大分解速率温度和残炭量均增大,但其断裂强度略有下降;当w(BGDTP)为20%时,阻燃PVFM纤维的LOI为30.8%,断裂强度为5.42 cN/dtex,最大热分解温度和残炭率比纯PVFM纤维均有较大幅度增加,燃烧形成连续致密的膨胀炭层。